An easy way to enable Telnet without modifying your firmware is to install Fonz funplug. (More info here). You can rollback your changes (and remove telnet access) later on by simply removing Fonz funplug files and reboot.

It is commonly accepted that you can't harm your device this way (you still should know what you do when using telnet)

I (piotr) used Helge's instructions to build firmwares in order to modify Dlink's firmware version 1.05. Currently it adds telnet access on port 23 without password authentication. You can download and reflash via the web interface. Only telnet is added, the rest of the firmware functionality is left intact.

This allows you to do filesystem checks since running telnet from the ramdisk allows the raid/hard disks to be umounted, just umount them and run e2fsck.

Check the md5sum of the firmware you downloaded. (The firmware also embedded CRC, but better safe than sorry).

Reflash your DNS323 using the web interface

Wait at least 3 minutes to be sure the unit is reflashed correctly

If you enter via web interface and see the option to recreate the raid again, just reboot the unit with the power button so the old raid is recognised and run again.

Now you can operate as normal, but port 23 should be open with telnet access

I like this method better than running as fun_plug since the latter causes the FS not to be cleanly umounted, leading to filesystem corruption over time. Dlink's firmware is really crappy, and doesn't check the filesystem. I have informed Dlink about this fact.

You should be able to go back to an official firmware using the web interface update.

The first thing you need to do is to create a fun_plug. The minimum fun_plug for telnet access looks like this:

## Minimal fun_plug, only enables telnet## Requires: /mnt/HD_a2/starttelnet.sh# /mnt/HD_a2/lnx_bin/busybox3# /mnt/HD_a2/lnx_bin/utelnetd### Uncomment next line if you want "proof of concept".
# A filem dmesg.out will be located on \\NAS\HDD_1 or # \\NAS\Volume_1 depnding on firmware version.## dmesg > /mnt/HD_a2/dmesg.out## Start the telnet deamon#
/mnt/HD_a2/starttelnet.sh

Next step is to dowload the files required. KRH kindly provided them for us and you can now download them from here: utelnet-kit.tar.gz. For Windows Users: Dont use WinZIP - try 7-Zip or WinRAR instead

When all files are extracted you need to install them. This can be achieved in several ways covered in the fun_plug howto. The most important is that the files resides on the first disc and in the following structure and that they have rights to execute.

So; now you have a telnet access and want to do something with it. Maybe a debian Sarge chroot system. Upgrade your iTunes server or make your ftp server working in a NAT'ed environment. You can even set-up your own WEB server using lighttpd.

But remember, always have fun, , and be aware that you're now in a position where you can easily brick your unit.